Thermal polymerization of petroleum hydrocarbon fraction



u ittid THERMAL POLYMERIZATION OF PETROLEUM HYDROCARBON FRACTIQN Claims priority, application Great Britain July 3, 1953 14 Claims. (Cl. 260-82) This invention relates to a process for the production of polymers. More particularly it relates to a process for the production of hydrocarbon polymers including residual polymers, from petroleum.

it is known that cyclopentadiene, by the action of heat, undergoes polymerization with formation of the dimer and higher polymers and that cyclopentadiene is usually a constituent of gasoline obtained by the cracking of naphthas. By the treatment of a C cut from such gasolines, followed by distillation, it is possible to obtain a dicyclopentadiene fraction which has applications in drying oil, paint and varnish manufacture, since, by reaction with vegetable drying oils, products are obtained which are superior to vegetable drying oils alone.

In has hitherto been disclosed that by the heat treatmerit of a distillation fraction of a steam cracked naphtha, said fraction containing polymers of cyclopentadiene and its homologues, it is possible to depolymerize said polymers to monomers.

We have found that under conditions of longresidence time at elevated temperatures and pressure, some of the C and higher constituents of a distillation fraction obtained by cracking a petroleum out are converted to valuable resinous polymers.

It is an object of the present invention to provide a process for the production of new hydrocarbonpolymers, including resinous polymers.

According to the present invention there is provided a process which comprises subjecting a cracked hydrocarbon fraction of petroleum origin having an initial boiling point of at least C. and a final boiling'point not higher than 200 C., to a heat treatment in the liquid phase at a temperature in the range 100 300. C. and at a pressure in the range 50-2000 lbs/sq. in. gauge for a period of at least 30 mins. and thereafter distilling the product to recover a hydrocarbon polymer fraction.

Preferably the cracked hydrocarbon fraction has an initial boiling point in the range 15-120 C. and in particular in the range 15-50 C. and a final boiling point in the range 140 to 200 C.

For ease of separation of distillate polymer as distinguished from resinous polymer, as described hereinafter, and in order to obtain maximum recovery of this product, it is' preferred that the feedstock fractions, which boil within the range 15-200 C., have a boiling range extending over not more than 100 C. within this range.

According to a modification of the process of the pres.- ent invention, said process comprises subjecting a cyclopentadiene-containing cracked hydrocarbonfraction of petroleum origin. having an initial boiling point in the range 15 to:30 C. and a finalboiling point in. the" range 50-70 C.. to a preliminary heat treatment ata temperature in the range 70-120 C., whereby cyclopentadiene tes Patent 0 2,817,647. Patented 'Dec. 24, 1957' In general a suitable cracking stock is a petroleum dis tillate fraction, for example, naphtha, gas oil or primary: flash distillate. The preferred feedstock to the cracking is a petroleum naphtha. More particularly it is preferred" that a naphtha cut boiling within the range to 250 C. is subjected to steam cracking. Suitably the naphtha is cracked at a cracking coil exit temperature in the range 600 to 750 C. and at a pressure in. the range from at mospheric to about 200 lbs/sq. in.

A particularly preferred feedstock is a cracked naphtha traction having an. initial. boiling. point in the range 35 to 50 C., and a final boiling point in the range 140' to 170 C. obtained by steam cracking a 90 to 210 C. naphtha cut at a cracking coil exit temperature of 670 to 730 C.

Themain heat treatment maybe carried out at a tem perature in the range -250 C. or. higher fora period" of time dependent upon the temperature of the treatment but usually within the range l-12 hours. Preferably the treatment is carried out at a temperature in the range l50275 C. and for 3-6 hours. The pressure should be sufiicient to maintain the feedstock. in the liquid phase at the temperature employed for the heat treatment and in general be at least 50 lbs/sq. in. although lower pressure can. sometimes be used with high boiling fractions of the cracked product. The upper limit of pressure is not generally critical. However, there is little advantage in using pressures exceeding the bubble point pressure of the feed at the temperature of the treatment.

Preferably the distillation of the heat treated cracked hydrocarbon fraction, wherein a resinous polymer fraction is recovered, is ettected with separate recovery of a gasoline fraction, a distillate polymer fraction and a resinous polymer fraction.

It is particularly preferred that the heat treated product is distilled at atmospheric pressure to remove a gasoline fraction overhead, and to recover a polymer fraction under reduced pressure, preferably below 300 mm. Hg, or is distilled in the presence of steam to recover a distillate polymer fraction overhead and: a fraction containing resinous polymers as bottoms.

It has been found that by distillation under reduced.

pressure or in the presence of steam, it is possible to avoid or reduce deterioration in the color and physical properties of the resinous polymers.

In general, it is preferred to recover a distillate polymer fraction which has an initial boiling. point at least 10 C. above the final boiling point of the cracked hydrocarbon fraction subjected to heat treatment and a final boiling point in the range ZOO-300 C.

Thus, for example, the distillation of theheat-treated product may be carried out continuously. or batchwise to remove -a stabilized gasoline fraction boiling up to C., a distillate polymer fraction boiling in the range 170 to 250 C- and a residue polymer fraction boiling aboveabout 250 C- (all distillation temperatures being reduced to atmospheric pressure) when employing a feed germs? stock offinal boiling point in the range 140-170 C.

It is desirable that air or oxygen-containing gases be excluded during the process and, in particular, during the heat treatment and distillation stages in order to obtain products of good color.

The distillate polymer fraction obtained according to this invention has been found to be suitable material for use as a component in a drying oil mixture. Thus this fraction may be used as a turpentine substitute. It may also be used as an additive to vegetable drying oils (for example linseed, tung and tall oils) to improve their film forming properties, and may be incorporated into natural or synthetic resins used in the surface coating industry. Preferably this distillate polymer fraction has: an initial boiling point in-the-range 130 to 200 C. and a final boiling point in the range 200300 C. .Furthermore, it has been found that the resinous polymers produced according to this'invention are of good color and will dry to hard films, with or without the addition of drying agents such ascobalt salts. They also form hard elastic films when baked on to surfaces either alone or with the addition of small amounts of vegetable drying oils or semi-drying oils or other plasticizers. Thus the residual polymers prepared in the examples described hereinafter gave hard films free from tack when painted on to steel sheet and baked at 100- 150 C. for 1-4 hours.

It is believed that the good qualities of the polymers which are obtainable by the process of the invention are attributable to the formation of novel polymer mixtures obtained by interpolymerization of constituents of the wide boiling range feedstock to the heat treatment.

It has also been ascertained that the recovered gasoline fraction is much superior to the feedstock, particularly in respect of stability and gum forming characteri'stics.

- The invention is illustrated but in no way limited by the following examples.

EXAMPLE 1 The feedstock treated was a 35 -145 C. fraction of gasoline prepared by steam cracking a naphtha fraction from Middle East crude oil, the cracker coil exit temperature being 1325 F. The fraction was heated for sixhours at a temperature of 150 C. under its own vapour pressure (250 lbs/sq. in. gauge). After .this treatment the product was distilled at 9 mm; of mercury pressure. Distillation of the residue was continued at 12 mm. of mercury pressure. Bromine numbers quoted were determined by the Kauffman method. The results obtained are shown in the following Table l.

The ratio of residual polymer to distillate polymer increased steadily during the six hours heat treatment. The total amount of residual polymer and distillate polymer also increased during the six hours. The experimentwas repeated with a heat treatment time of 12 hours. It was found that duringthe second 6 hours period there was only a slow increase in the total of residual polymer and distillate polymer product formed and in the ratio of residual polymer to, distillate polymer, using the same cut point between residual polymer and distillate polymer in the distillation of both products.

EXAMPLE 2 The experiment was repeated using a -142 C. cut of cracked gasoline produced as described in Example 1. Heating was continued for six hours at a temperature of 155 C. and the product distilled as before. The experiment was repeated with a heat treatment time of 12 hours. The results are summarized in Table 2.

' Table '2 Wt. percent Bromine Refractive of feed Number Index (42- 142 C. (Kaufi- 1m out) man) Feed 100 80 1. 4541 After 6 hours heating:

Gasol ne fraction 85 71 1. 4497 38-50 C./l0 mm 4.1 39 l. 4755 60 C./l0 rnm 3.0 57 1. 4813 6082 C./l0 mm..- 3. 7 114 1. 4920 Residual polymer.. 4. 2 135 After 12 hours heating:

Gasoline fract on 83 73 1. 4457 3057 G. 5 mm 6. 7 43 1. 4773 57-80 O./7 mm 4. 9 03 1. 4.873 8097 0.]3 5 mm" 1.4 151 1.5016 Residual polymer 4. 0 100 EXAMPLE 3 A crude gasoline distillate obtained by steam crackgenerated were as follows:

ing a naphtha cut from Middle East crude with a cracker coil exit temperature of 719 C. was heated under autogenous pressure in an agitated. steel autoclave at C. for 6 hours. The run was repeated using heart cuts of the gasoline. The boiling ranges of the feeds to the thermal treatment and the autogenous pressures Table 3 Pressure. Boiling Range of Feed to Thermal treatment lb./sq. in.

. gauge The products were separately distilled to recover unchanged gasoline redistilled and under reduced pressure to separate distillate polymer and residual polymer.

The yields of distillate polymer and residual polymer obtained are shown in Table 4:

When the crude gasoline was employed as feedstock to the thermal treatment, a distillate polymer fraction was not isolated, the components thereof being mainly recovered with the overhead fraction. However, the residual polymer obtained from the crude gasoline was of good quality, comparable with that made from the 40-150 C. out although of slightly darker color.

EXAMPLE 4 This example illustrates the batchwise operation of the process on a wide boiling feed, and also shows the effect of polymerization temperature on the product yields. A cracked distillate of boiling range -200 C. from the steam cracking of naphtha under substantially the same conditions as these used in preparing the feedstock of Example 3 was thermally polymerized under various conditions. The product was distilled to separate recovered gasoline boiling up to 200 C.

The bottoms were redistilled at a pressure of 5-50 mm. of mercury to recover distillate polymer boiling over the range ZOO-300 C. (corrected to 760 mm). The polymerization conditions and product yields are shown in Table 5. .All yields are as weights percent of the cracked distillate feed.

The yield of residual polymer increased continuously with rise in polymerization temperature, the yield of distillat'e polymer varying relatively little. At polymerization temperatures over about 270 C. darker colored residual polymers were obtained. The product obtained at 300 C. had a distinct color, and the odor of the gasoline recovered at this temperature was also inferior. For this reason polymerization temperatures below about 275 C. are preferred, although higher temperatures may be used in conjunction with shorter residence times, especially when the color of the residual polymer is not critical.

Table 5 Run No 88 93 105 94 99 Polymerization Conditions:

Pressure lbs/sq. in. gauge 150 180 180 280 500 Temp.,O 156 200 200 250 300 Time, hours .l 6 6 6 6 6 Recovered Gasoline (up to 200 C./

Yield, Wt. percent 89.1 84.1 84.6 79.8 73.150 Bromine No 56 57 48 36 Distillate Polymer (ZOO-300 0/760 Yield. Wt. percent 8.3 8.9 9 8.6 7.8 Residual Polymer:

Yield, wt. percent 2.6 7.0 6.4 .6 19.1 Bromine No 80 83 69 82 EXAMPLE 5 The results obtained by thermal polymerization of a cracked distillate prepared by steam cracking a primary flash distillate are shown in Table 6. This cracked distillate contained much more lower boiling (C -C hydrocarbon, and only small quantities of material boiling over 120 C./760 mm. The products were recovered in the same way as in Example 4, except that two fractions of distillate polymer were collected, and the recovered gasoline was collected up to 135 C.

The yields of residual polymer in this case were considerably less than from the naphtha cracking product of 15-200 C. boiling range, the products being very similar to those obtained from the 40-150 C. cut of the cracked distillate from naphtha.

Table 6 Run N0 118 119 122 123 Steam Cracking (coil exit) Temp. in 1 feed production "0 719 719 732 732 Polymerization Conditions: 1

Pressure, lbs/sq. in. gauge 380 1, 330 400 1, 480 Temp, 200 250 200 250 Time, hours 6 6 6 6 Recovered Gasoline (up to C 1 Yield, wt. percent 86.6 83.8 83.0 81.0 Bro mine No 45 51 68 62 Distillate polymer (l35200 0.):

Yield. wt. percent 8.7 9. 6 11.1 11.1 Bromine No 154 146 164 163 Distillate Polymer (ZOO-300 0.):

Yield. wt. percent 3. 2 3. 5 3. 7 3. 7 Bromine 186 186 185 180 Residual Polymer:

Yield, Wt. percent 1. 5 3. 1 2. 2 4. 2 Bromine N o -l 131 133 132 137 The residual polymers produced by distillation to an end point of 300 C./ 760 mm. are viscous liquids or semisolid resins. Further distillation, preferably under reduced pressure to avoid darkening of the resins by excessive still-bottom temperatures results in the removal of further volatile products leaving solid resins as residual products. This is illustrated by the following example.

EXAMPLE 6 Residual polymers boiling over 300 C. produced from steam-cracked naphtha as described in Example 4 were further distilled under a pressure of about 5 mm. of mercury. Solid products were obtained on which softening points (ring and ball) were determined. The results are summarized in Table 7.

It appears from these results that somewhat higher melting resins are obtained at a polymerization temperature of 200 C. than at 250 C. for the same end point in the distillation of the residual polymer, although higher yields are obtained at 250 C.

Continuous tests have been carried out in a stainless steel tubular reactor 15" long and 1.6 internal diameter, the liquid feed being pumped up flow through this reactor. The products were separated by distillation in the same way as in the batch tests described above. Illustrative results obtained are shown in Table 8, which gives the product yields and reaction conditions for a number of these tests. The feed was a cracked distillate obtained by the steam cracking of naphtha at 719 C.., as used in Examples 3 and 4.

Products made by heat treatment at temperatures in excess of about 275 C. tended to be darker in color than products produced at lower temperatures, and temperatures in the range ZOO-275 C. are therefore preferable whenit is desired to produce resins of'pale color. 1

Table 8 Run N 1 8 4 7 8 12 16 18 21 Conditions of Polymerization:

Temperature, "C 200 230 230 300 299 275 250 275 250 Pressure, p. s. i. g.-. 300 300 300 330 330 330 330 330 300 Residence, hours 1.0 0.5 1. 0 1. 0 0.5 2.0 3.0 4. O 4. 0 Product data:

Recovered Gasoline, 200 0. end point- Wt. percent on feed. 89. 85 88. 7 82. 75 84. 1 83. 6 83. 7 82. 2 84. 2 Bromine N0 63 80 61 61 60 50 62 55 61 Distillate Polymer, 200 00 Wt. percent on feed 9. 85 7. 85 8. 6. 5 7. 6 6. 95 8.85 7.05 8. 2 Residual Polymer. Over 300 C.

Wt. percent on feed 2. 2. 8 3. 25 10. 75 8. 9. 7. 45 10. 75 7. 6 Bromine No 94 106 71 91 101 70 60 61 65 EXAMPLE 8 A naphtha cut from Middle East crude was steamcracked with a cracker coil exit temperature of 719 C., a crude gasoline boiling over the range l5-200 C. being polymer fraction under reduced pressure to recover a distillate polymer fraction as overhead and said residual polymer fraction containing resinous polymers as hottoms.

20 5. A process as specified in claim 3 in which the heat 2 33 2? :zg ggt gg i fi g g gasoline treated prodi ct is distilled at atmospheric pressure to reby further distillation and subjected to a preliminary heat move a ggso me fracuon overhead: i recoyer a poly treatment at 100 C. for 8 hours to dimerize the cyclomer f l as bottoms thereaftel dlstlumg Sa.ld P y pentadiene contained therein The product was distilled fraction in the presence of steanrto recover said distillate to remove dicyclopentadiene as bottoms, the overhead 25 Polymer fr.ac.tlon oYerhead and sald resldual polymer frac' product being subjected to further heat treatment in an contammg i q agitated steel autoclave at 150-160 C. for 6 hours, the A P F as spe1fied cla1 m 4 m i h the i pressure generaied being 290 in gauge. The non containing resmous polymers is further distilled while product was distilled at atmospheric pressure to recover mamtammg the Pamal PresSure P the overhead prtfduct overhead, unchanged gasoline, the bottoms being further below 300 Of y, with recovery of re81110115 distilled under reduced pressure to separate distillate poly- P y as bottomsmerand resinous polymer fractions. The yields obtained 7. A Process as Specified in Claim 3 in Which the are shown in Table 9. tillate polymer fraction has an initial boiling point in the Table 9 Polymer Distillate Residual Polymer Boiling Range of feed to Thermal Treatment, O./760 mm. Yield wt. Yield wt.

Boiling Range percent Bromine percent Bromine of out No. of cut N o. processed processed 20-58" 0 (Oyclopentadiene free) 3851/12191 mm.66/10 5. 3 228 310 118 We claim: range l30200 C. and a final boiling point in the range 1. A process for the production of hydrocarbon poly- 200-300 C. mers which comprises subjecting a cracked hydrocarbon 8. A process for the production of hydrocarbon polyfraction of petroleum origin having an initial boiling mers which comprises subjecting a cracked hydrocarbon point in the range 15 -120 C. and a final boiling point fraction having an initial boiling point in the range 15 in the range of 140-200 C., to a heat treatment in the 120 C. and a final boiling point in the range 140-200 liquid phase at a temperature in the range l50300 C. C., and obtained by steam cracking a petroleum naphtha and at a pressure in the range 50-2000 lbs/sq. in. gauge fraction boiling in the range 90-250 C., to a heat treatfor a period of at least 30 mins. and thereafter distilling merit in the liquid phase at a temperature in the range the product to recover a hydrocarbon polymer fraction. l50-300 C. and at a pressure in the range 50-2000 2. Aprocess as specified in claim 1 in which the cracked lbs/sq. in. gauge for a period of at least mins. and hydrocarbon fraction is a cracked naphtha fraction havthereafter distilling the product to recover a gasoline fracing an initial boiling point in the range 35 to 50 C., tion, a distillate polymer fraction and a residual polymer and a final boiling point in the range 140 to 170 C. fraction. obtained by steam cracking a to 210 naphtha cut at 60 9. A process as specified in claim 12 in which the seea cracking coil exit temperature of 670 to 730 C. ond heat treatment, wherein hydrocarbon polymers are 3. A process for the production of hydrocarbon polyproduced, is carried out at a temperature in the range mers which comprises subjecting a cracked hydrocarbon -275 C. fraction of petroleum origin having an initial boiling point 10. A process as specified in claim 9 in which the secin the range 15-120 C. and a final boiling point in the 65 and heat treatment, wherein hydrocarbon polymers are range C.-200. C., to a heat treatment in the liquid produced, is carried out at a pressure in the range 100- phase at a temperature in the range -300 C. and 2000 lbs/sq. in. gauge. at a pressure in the range 50-2000 lbs./ sq. in. gauge for 11. A process as specified in claim 10 in which the heat a period of at least 30 mins. and thereafter distilling the treatment, wherein hydrocarbon polymers are produced, product to recover a gasoline fraction, a distillate poly- 70 is carried out for a period of 3-6 hours. mer fraction and a residual polymer fraction. 12. A process for the production of hydrocarbon polyv 4.' A process as specified in claim 3 in which the heat mers which comprises subjecting a cycl0pentadiene-contreated product is distilled at atmospheric pressure to taining cracked hydrocarbon fraction ofpetroleum origin remove said gasoline fraction as overhead, and to recover having an initial boiling point in the approximate range "a polymer fraction as bottoms, thereafter distilling said 75 15 to 30 C. and a final boiling point in the .range..50

to 70 C. to a preliminary heat treatment at a temperature in the range 70-120 C., whereby cyclopentadiene i contained in the fraction is converted to its dimer, thereafter distilling the product to remove said dimer, subjecting the cyclopentadiene free cracked hydrocarbon fraction obtained overhead to a heat treatment at a temperature above the temperature of said preliminary heat treatment and at a superatrnospheric pressure, and distilling the product to recover a hydrocarbon polymer fraction.

13. A process for the production of hydrocarbon polymers which comprises subjecting a cyclopentadiene-containing cracked hydrocarbon fraction of petroleum origin having an initial boiling point in the approximate range 15' to 30 C. and a final boiling point in the range 50 to 70 C. to a preliminary heat treatment at a temperature in the range 70-120 C., whereby cyclopentadiene contained in the fraction is converted to its dimer, thereafter distilling the product to remove said dimer, subjecting the cyclopentadiene free cracked hydrocarbon fraction obtained overhead to a heat treatment for a period of at least 60 minutes at a temperature above the temperature of said preliminary heat treatment and at a superatmospheric pressure, and distilling the product to recover a gasoline fraction, a distillate polymer fraction and a residual polymer fraction.

14. A process as specified in claim 13 in which the distillate polymer fraction has an initial boiling point in the range l30-200 C. and a final boiling point in the range 200-300 C.

References Cited in the file of this patent UNITED STATES PATENTS 2,067,073 Carmody Jan. 5, 1937 2,211,038 Ward Aug. 13, 1940 2,521,022 Rowland Sept. 5, 1950 

3. A PROCESS FOR THE PRODUCTION OF HYDROCARBON POLYMERS WHICH COMPRISES SUBJECTING A CRACKED HYDROCARBON FRACTION OF PETROLEUM ORIGIN HAVING AN INITIAL BOILING POINT IN THE RANGE 15*-120*C. AND A FINAL BOILING POINT IN THE RANGE 40*C,-200*C., TO A HEAT TREATMENT IN THE LIQUID PHASE AT A TEMPERATURE IN THE RANGE 150*-300*C. AND AT A PRESSURE IN THE RANGE 50-200 LBS./SQ. IN. GAUGE FOR A PERIOD OF AT LEAST 30 MINS. AND THEREAFTER DISTILLING THE PRODUCT TO RECOVER A GASOLINE FRACTION, A DISTILLATE POLYMER FRACTION AND A RESIDUAL POLYMER FRACTION. 